1. Field of the Invention
The subject invention relates to converting machinery, and more particularly to, a carriage assembly and an automated knife positioning system for score slitting machines, razor slitting machines and shear slitting machines.
2. Description of Related Art
For decades the converting industry has been employing score slitting machinery to convert webs of paper, foam, fabrics, nonwovens, tape and other materials into desired widths. A prior art score slitting machine for processing media is illustrated in FIG. 1 and is designated generally by reference numeral 10.
Referring to FIG. 2, slitting machine 10 includes a hardened score roll 12 against which media is slit or otherwise cut into desired widths, as the media is conveyed from an unwind which supports a web of uncut media to a rewind which accumulates the media after it has been cut into the desired widths. Slitting machine 10 further includes a carriage assembly 14 for supporting a plurality of score knives for slitting the media into desired widths.
More particularly, carriage assembly 14, as is known in the prior art, supports a plurality of pneumatic knife holders 16 on a horizontal support bar 18 in spaced relationship. The knife holders vary in size, but the most common knife holders are ½″ wide. Dozens of knife holders can be positioned on the support bar at one time to perform a slitting operation.
The support bar 18 has a dovetail configuration, as best seen in FIG. 2, which facilitates the ready removal and manual positioning of the knife holders 16 in a desired location by way of clamping screw 20. Each knife holder 16 carries a rotary score knife 22 and is connected to a common air manifold 24 by way of an air hose 26. In use, air pressure is applied to the knife holders 16 and regulated to achieve a desired cutting pressure against the score roll 12.
There are certain limitations associated with prior art score slitting machines. One such limitation is the significantly long set up time that is required to manually position the score knives on the support bar and ensure the accurate placement thereof. Another limitation specifically related to prior art automated knife positioning systems is that the slit width that can be achieved is generally limited by the set up distance that is required between adjacent knife holders mounted on the support bar. Thus, there is a minimum slit width that can be achieved with automated knife positioning systems on prior art slitting machines that is insufficient for many converting applications.
Clearly there is a need for a carriage assembly for knife holders that can overcome the limitations of prior art slitting machines, and that can be readily employed with other types of converting machines, including razor slitting machines and shear slitting machines.